Wayne Rooney rattled in his second hat-trick of the season as United regained pole position in the Premier League.

The England striker now has eight goals from his first four league games and is clearly enjoying his renewed partnership with Javier Hernandez, who contributed the other two on his first start of the season.

Manchester City had temporarily replaced their neighbours after defeating Wigan Athletic 3-0 earlier in the afternoon, but United made short work of restoring the old order, effectively having the match won within the first 20 minutes, by which time Hernandez and Rooney had both opened their respective accounts.

With maximum points from their first four games, and 18 goals scored in the process, it would be a foolish, rather than brave punter who bets against the champions retaining their title.

Just 20 motorway miles separate these two clubs, but in terms of resources they operate in different worlds, and the class gap was in evidence as United took a 3-0 lead, and a vice-like grip on the game, within 25 minutes. The identity of the scorers was scarcely a shock, Hernandez touching home the first from close range after five minutes when Nani's inviting cross from the right was met at the near post by the predatory Mexican, then Rooney adding two of his own.

The composition of the United team was always going to be interesting, four days before they launch their latest Champions League campaign away to Benfica, and such is their strength in depth that Alex Ferguson could make changes after the 8-2 drubbing of Arsenal and still field what was, arguably, a better starting 11.

Rio Ferdinand returned at centre-back with one England defender, Phil Jones, replacing another, Chris Smalling, at right-back, to hugely beneficial effect. In attack Hernandez, in scoring form for Mexico recently, replaced the injured Danny Welbeck. There had been some talk of Ferguson "resting" David de Gea -- a euphemism for sparing him a physical battering by Kevin Davies and company -- but the Spaniard kept his place in goal.

Changed line-up or not, United were impressively cohesive and penetrative from the start. Bolton introduced Mark Davies in midfield, to the exclusion of Fabrice Muamba, and gave a debut at right back to Dedryck Boyata, on loan from Manchester City. Their other recent signings, David N'Gog and Gael Kakuta, started on the bench. Poor Owen Coyle. If he was expecting an improved performance, he got just the opposite, United running through his team virtually at will. Jones, in particular, was allowed to rampage forward from the back unhindered, crossing from the right for Rooney to nudge in at the far post, then running through the middle, past two defenders before again creating the panic which enabled Rooney to score again, from eight yards.

"Are you Arsenal in disguise?" came the mocking inquiry from the visiting supporters.

Hernandez had the ball in the net again before half time, but from an offside position. Bolton had a shell-shocked look about them as they trooped off. They had created chances of their own, Rooney clearing a shot from Chris Eagles off the line and Ivan Klasnic demanding a spectacular save from De Gea. In truth, however, they were second best by a considerable distance.

The second half followed much the same pattern. Klasnic tried his luck from distance, to no avail, with United much more threatening. Hernandez was denied his second by Nigel Reo-Coker's goalline intervention. He did not have long to wait. A pinball sequence in Bolton's penalty area, initiated by Nani's mazy run, enabled the Mexican to make it 4-0 with a characteristically cool finish after 58 minutes.

Still United were not satisfied, Rooney scoring his third ten minutes later, when his shot from 18 yards nestled low inside Jaaskelainen's right-hand upright.